This invention relates to power distribution systems, and particularly to arrangements for measuring parameters of power lines and for using the measurements to control the conditions of the lines.
To maximize efficiency of energy use, and meet growing demands, utilities must automatically adjust their power transmission by detecting conditions as they happen. This involves simultaneous measurement of currents and voltages so that phase conditions can be determined, and using the results for control of the system. Methods and means of measurement are shown in U.S. Pat. Nos. 3,363,174 and 3,386,059, as well as in the aforementioned U.S. Pat. application.
The arrangements described in the above patents are inadequate for growing future demands. The aforementioned application includes an arrangement for measuring fundamental parameters such as voltage, current, and phase of electric power distribution or transmission lines in an economical manner. However, the signal conditioning equipment of the system is connected conductively to the transmission line ground. In the event of a lightning strike or other transient, the transmission line ground can be temporarily elevated thousands of volts. This may result in burn out of the signal ground or the signal conditioning equipment.